The present invention relates to a system for transmitting the power of an engine to four wheels of a four-wheel drive vehicle.
In a conventional four-wheel drive vehicle having a central differential, which is called a full time four-wheel drive vehicle, the central differential operates to uniformly distribute the torque of an engine to the front wheels and to the rear wheels of the vehicle.
It is known that the distribution ratio of the torque influences the driveability, steerability, stability, and starting characteristic of the vehicle. Namely, when the distribution to the front wheel is increased, a stable cornering characteristic at high vehicle speed is established, and when distribution to the rear wheels is increased, steerability at low vehicle speed is improved. In the conventional four-wheel drive vehicle, the distribution ratio of the torque for the front wheels to rear wheels can not be changed.